Erectile dysfunction, which is the persistent inability to attain and maintain penile erection sufficient for intercourse, is a major health issue among males and especially among the AX aging male population. The causes of erectile dysfunction include vasculogenic, neurogenic, endocrinologic and psychogenic. The etiology of erectile dysfunction is heterogeneous, yet, as id noted, is usually associated with vascular disease, endocrinopathy or a neural injury to the central or peripheral nervous system. Management options for erectile dysfunction depend on the cause of the dysfunction and include medical and surgical therapies and vacuum erection devices, each with their own limitations and complications.
Medical therapies include the oral, transcutaneous (penile injection) and transurethral (e.g. MUSE System) routes of delivery of various pharmacologic agents. See, for example, U.S. Pat. No. 5,916,569 to Spencer et al., U.S. Pat. No. 5,925,629 to Place, and U.S. Pat. No. 6,156,753 to Doherty, Jr. et al. However, many men are not suitable candidates for oral agents such as sildenafil (Viagra; Pfizer, New York), a phosphodiesterase inhibitor, because of potential life threatening interactions with cardiac medications such as nitrates.
Penile (intracavernosal) injection therapy with vasodilator agents such as prostaglandin E1, papaverine, nitric oxide, phentolamine, apomorphine, or vasoactive intestinal peptide (VIP) is a well-accepted method. The technique however must be taught to anxious patients with careful attention to the dose, injection sites, and the amount of the agent. Many patients withdraw from intracavernosal injection therapy because of the anxiety associated with self-injection, recurrent cutaneous ecchymoses, painful injections, or associated corporal fibrosis (Peyronie's Disease). Moreover, patients are uncomfortable when they travel through public airports or to foreign countries with syringes and medications. These limitations, associated with the complete loss of spontaneity, are the main reasons for discontinuation in an otherwise successful pharmacologic erection program.
Surgically invasive procedures have been reserved for those men who fail conservative therapies; these options include revascularization procedures, penile prostheses and cavernous nerve stimulation devices, e.g. U.S. Pat. No. 5,938,584 to Ardito et al. and U.S. Pat. No. 6,169,924 B1 to Meloy et al. Penile prostheses are generally last resort because implantation results in irreparable damage to the cavemosal tissue. Agents and devices specifically designed to stimulate the NVB of the phallus have not previously been successful because of the size of the NVB, sensitivity of the NVB to neural fibrosis, and extensive distal, neural damage resulting from surgical procedures such as a radical prostatectomy.